{twofish,aes}-{x86_64,i586} versus C implementations
From: Andi Kleen <hidden>
Date: 2007-08-20 00:34:33
Hallo, Currently there are two twofish and two aes implementions on x86. Worse when both are enabled as modules a modprobe aes will get the C version which seems to be slower on K8 and about the same speed on Core2 on my tests. Is there a specific reason why anybody would prefer the C functions over the assembler functions? Possible reasons I could think of: - If the assembler functions are optimized for a specific CPU the compiler might be able to do a better job on other CPUs. Is there evidence for this? I suspect it's not true. - They are not trusted and might be buggy. I assume they have been validated against the C versions with a wide range of input data, correct? If none of these reasons are valid it might make sense to disable the C versions for x86 and only offer the assembler versions. Then modprobe aes|twofish would DTRT automatically. Comments? -Andi